Several decades ago, a new roofing process was developed, whereby an asphalt roll, also referred to as an elastomeric modified bituminous roofing sheet, is unrolled and laid against a sheathing surface, a torch system being used between the asphalt roll and the sheathing surface for bonding the asphalt to the sheathing. During those years, experience has taught that the sheathing surface must be handled with care and that this system is fire hazardous, so that so that fire extinguishers are required for each torch unit at the immediate work area for the emergencies used as the sheathing surface caught fire. The sheathing is a wood substrate, such as a fiberboard, a wafer board, particle board and can even be plywood. Notwithstanding this problem since the 1950's, there has been no way of reducing these fire hazards.
Applicant has tried to develop a sheathing surface which would be fire resistant and yet would yield the suitable characteristics required for a sheathing surface. In particular, the sheathing surface must be such as to permit good and strong adhesion of the asphalt to it.
Applicant also aims at making a method which would not require substantial changes in the making of these wood substrates.
Among the preferred sheathing that is known, is a fiber board of mat-formed wood particles pressed and then dried to remove the excess water. The mat is formed by laying a wood pulp over a forming mat. Another sheathing which is known is a fiberboard wherein the wood particles pulp used for making the mat contains asphalt thereby yielding an asphalt impregnating sheathing.
One would think that such a wood sheathing would be easy to fireproof. Such is not the case, because fireproofing agents must be compatible with the sheathing and leave the functions of the sheathing umimpaired such as being able to form a good bond with asphalt. The bonding between the wood on the one hand and the asphalt on the other, is of the essence.